CLSimilarImages

CLSimilarImages is a command-line program for finding images which are visually similar to each other, even if they are not precisely the same. It can usually detect similarity despite recompression, resizing, stretching, and minor modifications. In classic Unix style, it is designed to be useful with pipes, in scripts, and in combination with other programs. It can search for matches in one collection of files, or compare two collections, and can store "thumbnails" of images on your system to make future comparisons faster.